The known prior art can be divided into four general catagories. Firstly, there are the conventional nursing bottles comprising a glass body and a nipple carrying cap which screws onto the upper end of the glass body. A typical example of this type of nursing bottle is disclosed by U.S. Pat. No. 2,808,167, granted Oct. 1, 1957 to Samuel Polazzolo.
Secondly, there are insulated containers for conventional baby nursing bottles. Examples of these are shown by U.S. Pat. No. 2,096,961, granted Oct. 26, 1937 to Bridget D. Condon, and by the aforementioned U.S. Pat. No. 2,808,167.
Thirdly, there are the well known thermos or vacuum type insulated bottles. Examples of these are disclosed by U.S. Pat. No. 1,388,189, granted Aug. 23, 1921, to George S. Meikle; by U.S. Pat. No. 2,833,436, granted May 6, 1958, to Max J. Ruderian and by U.S. Pat. No. 3,910,441, granted Oct. 7, 1975 to Carl Bramming.
Fourthly, there are baby nursing bottles which include a vacuum-wall receptacle of the type which is used in the aforementioned thermos or vacuum type insulated bottles. Examples of these are disclosed by U.S. Pat. No. 1,749,432, granted Mar. 4, 1930, to Elizabeth Kriege, and by U.S. Pat. No. 2,643,785, granted June 30, 1953, to Leonard W. Rust, Sr.
The bottle disclosed by Kriege, U.S. Pat. No. 1,749,432, does not employ a conventional nipple and both it and the bottle disclosed by Rust, Sr., U.S. Pat. No. 2,643,785, utilize resilient rubber materials or the like for centering the vacuum bottle within the outer housing or casing. These materials can readily absorb milk, dirt and other substances, are not easy to clean, and if frequently subjected to wash water will deteriorate over a short period of time.